These investigations are directed at the pathogenesis of viral respiratory illness in children. A long term prospective study of the prognosis of lower respiratory viral infection under three years of age is in progress, with particular emphasis on the development of allergy or asthma. A multi-factorial examination of immune factors in natural respiratory syncytial virus (RSV) disease has been performed which has demonstrated that young infants develop secretory IgA antibody on recovery from RSV infection. This antibody is apparently non-neutralizing. Studies of IgE antibody directed toward RSV are in progress, as are investigations of cell mediated immunity in RSV disease. BIBLIOGRAPHIC REFERENCE: McIntosh, K., Masters, H., Orr, I., Chao, R.K., and Barkin, R.M.: Secretory Antibody Following Respiratory Syncytial Virus Infection In Infants. Ped. Res. 10:389, 1976.